Melamine resins for improving surface properties of shaped articles of synthetic resins

ABSTRACT

A composition comprising (A) 100 parts by weight of an etherified methylolmelamine of the formula   WHEREIN R1 represents an alkyl group having 1 to 4 carbon atoms, (B) about 0.01 to 5 parts by weight of a nitrocellulose, (C) about 1 to 50 parts by weight of at least one alkyleneglycol selected from the group consisting of: H-OR2p-OR2OH and H-(OR2)m-X-(R2O)-H 7392/1965 wherein R2 represents -CH2CH2-, -CH2CH(CH3)- or -(CH2)4- group; p is 0 or a positive integer; X represents   GROUP WHEREIN R3 represents an alkylene group having 1 to 14 carbon atoms, phenylene or cyclohexylene group; R4 represents an alkylene group having 2 to 17 carbon atoms, phenylene or cyclohexylene group; R5 represents an alkyl group having 1 to 8 carbon atoms and when X represents   The compositions are heat-cured on the surfaces of shaped articles of synthetic resins. The heat-cured coatings are characterized by good hardness, mar resistance, abrasion resistance, antistat as well as good surface glass without losing the transparency of synthetic resins.

United States Patent 1191 Tanimura et al.

[ 1 Jan. 15, 1974 1 1 MELAMINE RESINS FOR IMPROVING SURFACE PROPERTIES OF SHAPED ARTICLES 0F SYNTHETIC RESINS [75] Inventors: Noboru Tanimura, Niza; Kenji Mori, Tokyo; Hirosi Tanaka, Niza,

all of Japan Asahi Kasei Kogyo Kabushiki Kaisha, Kita-ku, Osaka, Japan [22] Filed: Mar. 3, 1972 [21] Appl. N0.: 231,735

[73] Assignee:

[30] Foreign Application Priority Data Mar. 12, 1971 Japan 46/13078 June 1, 1971 Japan.... 46/37480 June 16, 1971 Japan.... 46/42493 July 23, 1971 Japan 46/54650 [52] U.S Il. 117/l38.8 B, 1-17/138.8 A, 138.8 N,

117/138.8 F, 117/138.8 R, 1l7/138.8 UA,

117/145, 117/161 C, 117/161 LN, 117/161 Primary Examiner-William H. Short Assistant Examiner-Edward Woodberry Alt0rneyBurgess, Dinklage & Sprung [57] ABSTRACT A composition comprising (A) 100 parts by weight of an etherified methylolmelamine of the formula wherein R represents an alkyl group having 1 to 4 carbon atoms, (B) about0.0l to 5 parts by weight of a nitrocellulose, (C) about 1 to 50 parts by weight of at least one alkyleneglycol selected from the group consisting of:

wherein R re resents -CH Cl-1 -CH CH(CH- or (CH group; p is 0 or a positive integer;

, X represents -OICVNHRNHCO- or R5N group wherein R represents an alkylene group having 1 to 14 carbon atoms, phenylene or cyclohexylene group; R represents an alkylene group having 2 to 17 carbon atoms, phenylene or cyclohexylene group; R represents an alkyl group having 1 to 8 carbon atoms and when X repre sents group R is CH CH group; m represents an positive integer; and n is an integer of l to 10, and (D) about 0.01 to 12 moles, based on one mole of said etherified methylolmelamine, of an acid catalyst.

The compositions are heat-cured on the surfaces of shaped articles of synthetic resins. The heat-cured coatings are characterized by good hardness, mar resistance, abrasion resistance, antistat as well as good surface glass without losing the transparency of synthetic resins.

20 Claims, No Drawings MELAMINE RESINS FOR IMPROVING SURFACE PROPERTIES OF SHAPED ARTICLES F SYNTHETIC RESINS This invention relates to novel compositions for improving surface properties of shaped articles of synthetic resins.

Generally synthetic resins are soft and the surfaces are apt to be marred on wiping off dust or scratching and the difficulty in preserving the beautiful appearance of synthetic resins such as glass and transparency for a long period lowers practical values of synthetic resins. Furthermore, synthetic resins are easily charged by friction and this charging promotes adhesion of dust and accelerates to have the surfaces of synthetic resins marred.

In order to avoid these disadvantages there are erriployed methods of coating surfaces of synthetic resins with thermal curing resins including, for example, melamine resins. But the adhesion of a melamine resin alone to a shaped article of synthetic resins is insufficient. In order to improve the adhesion several methods are already provided. Japanese Patent Publication No. 3989/1959 describes the coating of a shaped article of vinyl chloride resins or acrylic resins with a thermal curing resin such as a melamine resin and before application of the thermal curing resin a continuous film layer of a polyester type resin is formed on the surfaces of the shaped article. According to Japanese Patent Publication No. 7392/1965, in order to increase the surface hardness of a shaped article of styreneacrylonitrile type copolymers a mixture of an etherified methylolmelamine, a nitrocellulose and an alkyd resin is heat-cured in the presence of a polyfunctional carboxylic acid. Japanese Patent Publication No. 109/1971 relates to an improved process in which a mixture of an etherified methylolmelamine, a polyfunctional allyl compound or a polyfunctional vinyl compound, a nitrocellulose and a non-drying oil modified alkyd resin is heat-cured in the presence of a polyfunctional carboxylic acid and a radical polymerization catalyst and thus mar resistance of a shaped article is increased. However, according to Japanese Patent Publication Nos. 7392/1965 and 109/1971 when the amount of the etherified melamine is greater than that of the alkyd resin the compatibility of the both is poor and the mixture becomes easily opaque. The decrease of transparency and gloss is observed on the heat-cured shaped articles. 7 I

It is accordingly an object of this invention to provide a novel coating composition which gives a heat-cured product having good hardness, mar resistance, abrasion resistance, antistat as well as good surface gloss and transparency.

Another object of this invention is to provide a novel coating composition which substantially avoids the difficulties of prior art etherified methylolmelamine type coating compositions.

Other and additional objects of this invention will be- I come apparent from a consideration of this entire specification and claims.

wherein R represents an alkyl group having 1 to 4 carbon atoms, (B) about 0.01 to 5 parts by weight of a nitrocellulose, (C) about 1 to 50 parts by weight of at least one alkyleneglycol selected from the group consisting of:

group wherein R represents an alkylene group having 1 to 14 carbon atoms, phenylene or cyclohexylene group; R represents an alkylene group having 2 to 17 carbon atoms, phenylene or cyclohexylene group; R represents an alkyl group having 1 to 8 carbon atoms and when X represents li -N group R is Cl-1 CH group; m represents an positive integer; and n is an integer of l to 10, and (D) about 0.01 to 12 moles, based on one mole of said etherified methylolmelamine, of an acid catalyst.

Examples of suitable etherified methylolmelamines include hexakis(methoxymethyl)melamine, hexakis(ethoxymethyl)melamine, hexakis(n-propoxymethyl)- melamine, hexakis(isopropoxymethyl)melamine, hexakis(n-butoxymethyl)melamine, hexakis(isobutoxymethyl)melamine, hexakis(secbutoxymethyl)melamine and hexakis(tert-isobutoxymethyl)melamine.

The nitrocelluloses are employed for obtaining an increased adhesion to shaped articles of synthetic resins after heat-curing and preferably used in an amount of from about 0.01 to 5 parts by weight based on parts by weight of an etherified methylolmelamine. When the amount is less than about 0.01 part by weight, the desired effects are hardly realized. On the other hand, amounts of more than about 5 parts by weight remarkably increase the viscosity of a solution of coating compositions and consequently it is difficult to obtain a uniform and regular coating.

It is preferred that the nitrocelluloses have a nitrogen content of about 9 to 12.5 weight percent, more preferably 10.7 to 12.5 weight percent and an average degree of polymerization of about 30 to 1,000, more preferably 35 to 480.

The alkyleneglycols are employed for obtaining a desirable flexibility and mar resistance after heat-curing and preferably used in an amount of about 1 to 50 parts weight based on 100 parts by weight of an etherified methylolmelamine. When the amount is less than about 1 part by weight, the desired effects are hardly realized. On the other hand, amounts of more than about 50 parts by weight reduce the surface hardness of a coating.

Examples of suitable alkyleneglycols include ethyleneglycol, propyleneglycol, tetramethyleneglycol, polyethyleneglycols having an average molecular weight of up to about 100,000, polypropyleneglycols having an average molecular weight of up to about 10,000 and polytetramethyleneglycols having an average molecular weight of up to about 10,000; and modiocmcrno-Q-cm,

O i ii l 11 -o 'o NH(CH;);NHC o-, o 0 Nmcnnmncm,

o 0 15 ll -0 NH NH0 0- Carbonate modified polyalkyleneglycols may be prepared by reactingan alkyleneglycol with diethyl carbonate in the presence of metallic sodium as a catalyst acid, decanedioic acid, terephthalic acid, phthalic acid, isophthalic acid, 1,4-cyclohexylene dicarboxylic acid, l,2-diphenoxyethane-p,p'-dicarboxylic acid, and the like, in the presence or absence of p-toluenesulfonic acid as a catalyst under heating above 100C. Urethane modified polyalkyleneglycols may be obtained by reacting an alkyleneglycol with a diisocyanate such as ethylene diisocyanate, hexamethylene diisocyanate, 2,4-tolylene diisocyanate, 4,4-diphenyl-methane diisocyanate, 4,4'-(3,5,3,5-tetramethyldiphenylmethane) diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and the like in the presence or absence of a basic catalyst such a tertiary amine. Amine modified polyalkyleneglycols may be obtained by reacting under heating ethyleneoxide with a monoalkyl amine such as methylamine, ethylamine, n-butylamine, n-octylamine, and the like under a pressure.

In order to improve abrasion resistance to the friction of surfaces of shaped articles with paper or cloth under under heating at a temperature of from about C. to 6 C. Carboxylate modified polyalkyleneglycols may be prepared by reacting an alkyleneglycol with a dicarboxylic acid such as oxalic acid, succinic acid, adipic a load, about 0.1 to 20 parts by weight, based on 100 parts of an etherified methylolmelamine, of tetramethylsilicate or tetraethyl silicate is preferably added to the coating composition. When the amount of tetramethyl silicate or tetraethyl silicate is less than about 0.1 part by weight, the abrasion resistance is not significantly increased. On the other hand amounts of more than about 20 parts by weight retard the heat-curing reaction.

In order to color a heat-cured layer of the coating composition it is preferred that the coating composition additionally contains about 0.5 to 6 parts by weight, based on 100 parts by weight of an etherified methylolmelamine, of an oil soluble dye. When the amount is more than about 6 parts by weight, the adhesion to a shaped article diminishes and the coated layer tends to be easily peeled off. Also when the amount is less than about 0.5 parts by weight, coloring is very shallow. I

Examples of suitable oil soluble dyes include dyes corresponding to Color Indices, Solvent Yellow 2, t, 15,16,19, 21, 56, 61 and 80; Solvent Orange 1,2, 5, 6, 14, 37, 40 and 45; Solvent Red 1, 8, 23, 30, 49, 81, 82, 83, 84,100,109 and 121; Solvent Violet 8, 21, 27; Solvent Blue 12, 45, 55 and 73; Solvent Brown 20, 37; and Solvent Black 3, 5, 22 and 23.

Examples of suitable acid catalysts include hydrochloric acid, phosphoric acid, p-toluenesulfonic acid, oxalic acid and acetic acid. The acid catalysts are used in an amount of about 0.01 to 12 moles, preferably about 0.5 to 2 moles per mole of an etherified methylolmelamine.

The shaped articles of synthetic resins which may be coated with the compositions of this invention include, for example, plates, sheets, plastic lenses, covers of meters, covers of lighting fixtures, displays, and the like.

Examples of suitable synthetic resins include cellu lose derivatives such as cellulose diaeetates, cellulose triacetates, acrylonitrile-butadiene-styrene copolymers, polycarbonates, polyamides such as polycapramides, polyhexamethylene adipamidcs, polyhexamethylene sebacamides, polylaurolactams, unsaturated polyesters, polymethylmethacrylutes and methylmethacrylate copolymers containing about 0.5 to 15 mole percent of methylacrylate unit.

The solution of coating compositions are obtained by dissolving the above-mentioned components in a solvent. For shaped articles of polymethylmethacrylates, cellulose diacetates, cellulose triacetates, polycarbonates, polyamides, acrylonitrile-butadiene-styrene copolymers and unsaturated polyesters, it is preferred to use a mixture solvent essentially comprising (a) at least one alcohol selected from .methanol, ethanol, npropanol, isopropanol, n-butanol, isobutanol and tertiary butanol, (b) chloroform, (c) at least one acetate selected from methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, tertiary butyl acetate, n-amyl acetate, isoamyl acetate and n-hexyl acetate and (d) water. For shaped articles of methylmethacrylate copolymers containing about 0.5 to mole percent of methylacrylate unit, it is preferred to use a mixture solvent essentially comprising (a) at least one alcohol selected from methanol, ethanol, npropanol, isopropanol, n-butanol, isobutanol and tertiary butanol, (b) at least one ketone selected from acetone, methylethylketone, diethylketone, methylisobutylketone and cyclohexanone and (c) water.

To obtain a solution of coating compositions, an etherified methylolmelamine, a nitrocellulose, an alkyleneglycol and, if necessary, tetramethyl or tetraethyl silicate and an oil soluble dye are dissolved in the abovedescribed mixture solvent at a concentration of about to 70 weight percent. Separately, an acid catalyst is dissolved in or mixed with an alcohol such as methanol, ethanol or an alcohol-water to prepare an about 0.1 to 5 N solution. Then this acid catalyst solution is sufficiently mixed with the above-mentioned solution.

The solutions of coating compositions may be coated on shaped articles of synthetic resins by a brush or a spray gun. Also shaped articles may be immersed for about 10 seconds to 2 minutes.

The thickness of a layer of coating compositions is preferably about 0.5 micron to microns after heatcuring.

The shaped articles of synthetic resins coated with the compositions of this invention are subjected to curing reaction. The temperature of curing reaction is preferably from about 50C. to lower than the heat distortion temperature of synthetic resins and the time of curing reaction depends on the temperature and is generally from about 10 minutes to 10 hours.

This invention will now be illustrated by the following examples in which parts are all by weight unless expressly stated to contrary.

parts of urethane modified polyethylene glycol prepared by reacting polyethylene glycol having an average molecular weight of 1,000 and hexamethylene diisocyanate at a mole ratio of 3 2 and a desired amount of nitrocellulose having a nitrogen content of 11.9 weight percent and an average degree of polymerization of 85 set forth in Table l were dissolved in a mixture solvent consisting of 15 parts of ethanol, parts of chloroform, 15 parts of isobutyl acetate, 2 parts of n-amyl acetate and 3 parts of water. Separately, a 35 percent hydrochloric acid solution was diluted with methanol to obtain a 0.8 N solution. The resulting solution was mixed with the above-described solution at a volume ratio of l 1. After the resulting solution was left to stand at 20C. for one hour, a 6 cm. X 6 cm. cast plate of 3 mm. thick polymethylmethacrylate was immersed in the solution for 20 seconds. Then, the plate was removed from the solution and subjected to curing reaction at 100C. for 2 hours in a hot air drier. The thickness ofa coating was 3 microns. The plate thus obtained was subjected to the following tests and the results are shown in Table 1.

Adhesion: A grid of eleven horizontal and eleven vertical lines spaced 1 mm. apart is scratched by a razer blade through the coating into the plate beneath. Then a pressure sensitive tape is firmly attached to the grid and rapidly pulled away. Adhesion is shown by the number a sections which are not peeled off. For example, 100/100 shows that the 100 sections are all intact, which shows good adhesion.

Pencil hardness: Using a pencil hardness tester made by Nihon Rigaku Kogyo, the resin surface is scratched with a testing pencil at an angle of 45 under a load 1,000 grams. 1f scratches are seen in 3 to 5 tests out of 5, the testing pencil is replaced with another pencil lower by one rank and, in 1 to 2 tests, the hardness of the pencil used is shown.

Mar resistance: Tests for mar resistance are made in accordance with ASTM D-673-44. On a test specimen slant at 45", 400 g. of No. 80 mesh carborundum are dropped from a height of 25 inches.

Gloss retention is obtained by measuring specular gloss of the specimen thus treated with a gloss meter in accordance with Japanese Industrial Standard No. Z8741. 100 of gloss retention means the ,value obtained by measuring specular gloss of a specimen before mar resistance test. Also transmission retention is obtained by measuring transmission at 570 mu.

Specular gloss: Specular gloss is measured in accor- EXAMPLE 1 dance with Japanese Industrial Standard No. 30 parts of hexakis(n-butoxymethyl)melamine, 6 145400-1970.

Table 1 Mar resistance Amount of Film Gloss Transmission Run nitrocellulose performance Pencil retension retension No (part) coated layer Adhesion hardness l 0 Good 0/100 3H 25 67 2 0.003 Good 80/100 4H 48 70 3 0.03 Good 100/100 5H 63 4 0.3 Good /100 6H 70 '82 Table l ComiriuEE Mar resistance Amount of Film Gloss Transmission Run nitrocellulose performance Pencil retension retension No. (part) coated layer Adhesion hardness 5 1.5 Slightly irregular 100/100 5H 60 74 in thickness 6 3.0 Slightly irregular 100/100 4H 47 70 in thickness 7 3.5 Irregular 100/100 3H 40 68 in thickness Reference 3H 11 65 Uncouted plule Specular glull n1 uncmilctl plutc Wm 75'I1u1'lhut of united pltilc.

EXAMPLE 2 30 parts of hexakis(methoxy methyl)me1amine, a desired amount of urethane modified polyethylene glycol prepared by reacting polyethylene glycol having an average molecular weight of 1,000 and hexamethylene diisocyanate at a mole ratio of 2 1 shown in Table 2 and 0.3 part of nitrocellulose having a nitrogen content of 1 1.9 weight percent and an average degree of polymerization of 85 were dissolved in a mixture solvent consisting of 40 parts of ethanol, 48 parts of chloroform, 1 1 parts of isobutyl acetate and 1 part of n-amyl acetate. Separately, a 35 percent hydrochloric acid solution was diluted with methanol to obtain a 1.4 N solution. This solution was mixed with the above-described solution at a volume ratio of 1 2. After the resulting Then the plate was removed from the solution and subjected to curing reaction at 80C. for 2 hours in a hot air drier. The thickness of a coating was 2 microns. This plate was subjected to the same tests as in Example 1 and Antistat test. The results are shown in Table 2.

Antistat test: Saturated static charged and its half life time are measured by a Static Honestomer (made by Shishido Shokai). A sample is placed on a turn table and while rotating the turn table at 7,000 r.p.m., an electromotive force of 10,000V is impressed at a point and the charged static of the specimen is detected at the opposite. When the charged static is saturated, impress is stopped and then decay of the charged static is observed. Half life is defined as the time when the charged static becomes A of the saturated one. The sample, after plate solution was left to stand at 20C. for 1 hour, a 6 cm. 35 7 RH f 24 h d X 6 cm. cast plate of 3 mm. thick polymethylmethz z fg (1 25 7 H Ours an acrylate was immersed in the solution for 30 seconds. Sure at an 0 Table 2 Mar resistance Antistat Urethane modified Gloss Transmission Half life time of Run polyethylene glycol Pencil retention retention charged static No. (part) Adhesion hardness (72) (sec.)

Reference 3H 11 65 Uncoated EXAMPLE 3 30 parts of hexakis(methoxy methyl)melamine, 0.3 part of nitrocellulose having a nitrogen content of 10.5 weight percent and an average degree of polymerization of 150, 6 parts of a urethane modified polyethylene glycol prepared by reacting polyethylene glycol having a molecular weight of 1,000 and hexamethylene diisocyanate at a mole ratio of 3 2 and a desired amount of tetraethyl silicate shown in Table 3 were dissolved in a mixture solvent consisting of 15 parts of ethanol, 65 parts of chloroform, 15 parts of isobutyl acetate, 2 parts of n-amyl acetate and 3 parts of water. Separately, a 35 percent hydrochloric acid solution was diluted with ethanol to obtain a 0.8N solution. This solu- EXAMPLE 4 30 parts of hexakis(methoxymethyl)melamine, 1.5 parts of tetramethyl silicate, 1.5 parts of polyethyleneglycol having an average molecular weight of 400 and a desired amount of nitrocellulose having a nitrogen content of 10.5 percent and an average degree of polymerization of 150 set forth in Table 4 were dissolved in a mixture solution consisting of 49 parts of ethanol, 4 parts of n-butanol, 46 parts of methylethyl ketone and 1 part of water. Separately, a 35 percent hydrochloric acid solution was diluted with water to obtain a 1.0N solution. This solution was mixed with the abovetion was mixed with the above-described solution at a 15 described solution at a volume ratio of 1 1. After the volume ratio of 1 1. After the resulting solution was resulting solution was left to stand at 25C. for 5 hours, left to stand at 20C. for 1 hour, a 6 cm. X 6 cm. cast a 10 cm. X 10 cm. extruded sheet of3 mm. thick methplate of 3 mm. thick polymethylmethacrylate which ylmethacrylate copolymer containing 6 mole percent was well washed and dried was immersed in the soluof methyl acrylate was immersed in the solution for 30 tion for 25 seconds. Then the plate was removed from seconds. Then the sheet was removed from the solution the solution and subjected to curing reaction at 100C. and subjected to curing reaction at 80C. for 1 hour in for 1 hour. The thickness of coating was 3 microns. The a hot air drier. The thickness of a coating was 3 miplate thus obtained was subjected to the same tests as crons. The results of the same tests as in Example 3 toin Example 1 and abrasion test. The results are shown gether with half life time-of charge static are shown in in Table 3. Table 4.

Table 3 Mar resistance Amount of tetraethyl Film Gloss Transmission Run silicate of performance Pencil retention retention Abrasion No. (part) coated layer Adhesion hardness (96) (9%) resintance l 0 Good l00/l00 6H 69 300-320 2 0.003 Good 100/100 6H 70 320-340 3 0.03 Good l00 l00 6H 73 84 580-600 4 0.3 Good 100/I00 6H 75 35 720-740 5 3.0 Good loo loo 6H 71 83 760-780 6 5.0 Good loo loo 6H 73 85 760480 7 7.0 Uneven l00/l00 4H 58 70 560-580 Reference 3H ll 65 2-4 Uncoated Plate Specular gloss of uncoated plate was 75% of that of coated plate.

Table 4 Mar resistance Antistat Run Amount of Film of performance Adhesion Pencil Gloss Transmission Abrasion Half life time of No. nitrocellose coated layer hardness retention retention resistance charged static (sec.)

(part) I 0 Good 0/100 2H 19 50 l-2 5 2 0.003 Good 62/10 3H 45 62 l20-l40 5 3 0.03 Good /100 4H 58 72 240-260 4 4 0.3 Good /100 5H 64 78 300-320 4 5 1.5 Slightly irregular 100/100 4H 59 74 280-300 4 in thicknelm (u 2.0 Irregular in 100/100 3H 50 65 220-200 4 thickness Reference 7 2H 8 35 l2 8,000

Uncnatcd ltl'lCCi Abrasion: Tests for abrasion are made by using EXAMPLE 5 Sutherland Type Ink Rub Tester (made by Toyo Seiki Co., Ltd.). The surface of a sample is rubbed with filter paper (made by Toyo Filter Co., Ltd. Filter Paper No. 5C) under a load of 4 pounds. The number of traveling time at which the surface of 65 weight percent and having an average degree of polythe sample begins to be marred is shown. For ex-- ample, 100-120 means that the surface is not merization of I50, 0.3 part of polyethylene glycol having an average molecular weight of 2,000 or 0.3 parts of urethane modified polyethylene glycol prepared by reacting polyethylene glycol having an average molecular weight of 1,000 and hexamethylene diisocyanate at a mole ratio of 2 l were dissolved in a mixture solvent consisting of 50 parts of methanol, 7 parts of acetone, 40 parts of methylethyl ketone and 3 parts of water. Separately, a 35 percent hydrochloric acid solution was diluted with methanol to obtain a 1.0N solution. The resulting solution was mixed with the above-described solution at a volume ratio of l 1. After the resulting solution was left to stand at 25C. for 5 hours, a 6 cm. X 6 cm. extruded plate of 3 mm. thick methylmethacrylate copolymer containing 6 mole percent of methyl acrylate unit was immersed in the solution for seconds. Then the plate was removed from the solution and subjected to curing reaction at 80C. for 1 hour in a hot air drier. The results of tests are shown in Table 5.

D. Carbonate modified polyethyleneglycol obtained by reacting polyethyleneglycol having an average molecular weight of 1,000 with diethyl carbonate at a mole ratio of 2 l E. Carboxylate modified polyethyleneglycol obtained by reacting polyethyleneglycol having an average molecular weight of l,000 with adipic acid at a mole ratio of 2 1 F. Carboxylate modified polyethyleneglycol obtained by reacting polyethyleneglycol having an average molecular weight of 1,000 with isophthalic acid at a mole ratio of 2 z 1 G. Amino modified polyethyleneglycol obtained by reacting n-butylamine with ethyleneoxide at a mole Table 5 Half life Gloss Transmission time of Polyalkylene Pencil retention retention charged static glycol Adhesion hardness (36) (36) (sec.)

Polyethylene IOU/I00 4H 37 50 75 glycol Urethane IOU/I00 4H 43 58 73 modified polyethylene glycol Uncoated 2H 8 8,000 plate ratio of l 28 EXAMPLE 6 Procedure of Example 2 was repeated except that 5 H. Urethane modified polyethyleneglycol obtained by reacting polyethyleneglycol having an average parts of a polyalkyleneglycol shown below was used inmolecular weight of 1,000 with 4,4- stead of the urethane modified polyethyleneglycol and dicyclohexylmethane diisocyanate at a mole ratio the results of tests are shown in Table 6. of 2 1 Table 6 Antistat Mar resistance Half Gloss Transmission life time of Run Polyalkylene Pencil retention retention charged static Specular N0. glycol Adhesion hardness (70) (sec.) gloss 1 (A) 100/100 5H 62 74 l8 1 93 s (F) 100 100 5H 58 71 17 93 Specular gloss before coating is 75.

A. Polyethyleneglycol having an average molecular EXAMPLE 7 weight of 2,000

Procedure of Example 2 was repeated except that B. Polypropyleneglycol having an average molecular 65 various plates set forth in Table 7 were used instead of weight of 2,000 C. Polytetramethyleneglycol havingan average molecular weight of 2,000

the plate of polymethylmethacrylate and the urethane modified polyethyleneglycol was used in an amount of 5 parts. As for the plates of polyeapramide and poly- 13 hexamethylene adipamide the curing reaction was carried out at 60C. for hours. The results of tests are shown in Table 7.

EXAMPLE 9 30 parts of hexakis(n-butoxymethyDmelarhine, 1.5

Table 7 Run Plate No (thickness:mm.) Adhesion Pencil hardness Specular gloss l Cellulose diaeetate (0.25) 95/100 5H (2H") 120 2 Cellulose triacetate (0.25) 100/100 5H (211) 125 3 Acrylonitrile-butadiene-styrene copolymer (3) 100/100 3H (F) 120 4 Polycaprolactam (3) 96/100 3H (H) 125 5 Polyhexamethylene adipamide (3) 100/100 2H (F) 120 6 Polycarbonate (3) 90/100 3H (HE) 130 7 Unsaturated polyester (3) 100/100 5H (3H) 120 Note: Pencil hardness before coatirig (l) Cellulose diacctate made by Fuji Photo Film Co., Fuji Tac D" (2) Cellulose triaeetate made by Fuji Photo Film Co., Fuji Tac (3) Acrylonitrilc-butadiene-styrenc copolymer made by Asahi-Dow K.K., "Styrac 200" (4) Polycapramide made by Toray Co., Ltd.

(5) Polyhcxamethylene adipamirlc made by Asahi Kasei Kogyo K.K., "Leona 1300 (6) Polycarbonate made by Teijin Ltd., "Panlile" (7) Unsaturated polyester made by Takeda Pharmaceutical Co., "Polymal 8235-A" EXAMPLE 8 30 parts of hexakis(methoxymethyDmelamine, 0.6 part of tetraethyl silicate, 0.3 part of nitrocellulose having a nitrogen content of 11.9 weight percent and having an average degree of polymerization of 85 and a desired amount of urethane modified polyethylene glycol were dissolved in a mixture solvent consisting of 40 parts of ethanol, 48 parts of isobutyl acetate and 1 part of n-amyl acetate. Separately, a 35 percent hydrochloric acid solution was diluted with ethanol to obtain a 1.4 N solution. The resulting solution was mixed with the above-described solution at a volume ratio of l 2. After the resulting solution was left to stand at C. for 5 hours, a 6' cm.' 6 cm. cast plate of 3 mm. thick polymethylmethacrylate was immersed in the solution 20 seconds. Then, the plate was removed from the solu- 40- tion and subjected to curing reaction at 80C. for 1 hour in a hot air drier. The thickness of a coating was 2 microns. The same tests as in Example 4 were carried out and the results are shown in Table 8.

Table 8 parts of tetraethyl silicate, 0.3 part ol riitroceliilose having a nitrogen content of 11.9 weight percent and having an average degree of polymerization of 85 and 3.0 parts of a polyalkyleneglycol-set forth in Table 9 were dissolved in the same mixture solvent as in Example 3. Separately an about 35 percent hydrochloric acid solution was diluted with methanol to obtain a 0.8 N solution. This solution was mixed with the abovedescribed solution at a volume ratio of 1 1. After the resulting solution was left to stand at 20C. for one, a cast plate of polymethylmetha crylate was immersed in the solution for 25 seconds. Then the plate was removed from the solution and subjected to curing reaction at 100C. for 2 hours in a hot air drier. The thickness ofa coating was 2 microns. The results of tests are shown in Table 9.

parts of hexakis(methoxymethyl)melamine, hexakis(ethoxymethyl) melamine or hexakis(isopropoxymethyl)melamine, 0.25 part of nitrocellulose having -Amount Antistat f Mar resistance Half life polyethylene Gloss Transmission time of Run glycol Pencil retention retension Abrasion charged static No. (part) Adhesion hardness ('35) resistance (seq) 1 i 0' 100/100 4H 51 70 540-560 83 2 1.5 100/100 SH 70 85 580-600 20 3 10 100/100 5H 69 83 620-640 5 4 15 100/100 4H 80 660-680 4 S 20 100/100 3H 20 620-640 3 Reference 3H 1 l 65 2-4 Uncoated plate Table 9 Antistat Mar resistance Half life Gloss Transmission time of Run Polyalkylene Pencil retention retention Abrasion charged static No. glycol Adhesion hardness (91;) (9%) resistance (sec.)

1 (A) 100/100 5H 65 76 620-640 8 2 (B) 100/100 511 65 620-640 13 Table 9 -(oniinued Antistut Mar resistance Halt lifc Gloss Transmission time of Run Polyalkylene Pencil retention retention Abrasion charged static No. glycol Adhesion hardness resistance (sec.)

3 (C) 100/100 H 68 80 640-660 7 4 (D) 100/100 5H 65 77 640-660 7 5 (E) 100/100 5H 63 72 580-600 2 Reference 3H 11 65 2-4 Uncoatcd plate (A) Polyethylene glycol having an average molecular weight of 2,000 (B) Polypropylene glycol having an average molecular weight of 2,000 (C) Product prepared by reacting polyethylene glycol having an average molecular weight of 1,000 and diethyl carbonate at a mole ratio of 2 l 3 ..c (D) Product prepared by reacting polyethylene glycol having an average molecular weight of 1,000 and adipic I acid at a mole ratio of 2 1.

(E) Product prepared by reacting ethyleneoxide and n-butylamine at a mole ratio of 28 l.

a nitrogen content of l 1 .5 weight percent and having EXAMPLE 1 1 an average degree of polymerization of 85, 0.5 part of tetraethyl silicate and 0.5 part of urethane modified polyethylene glycol prepared by reacting polyethylene glycol having an average molecular weight of 1,000 and 30 parts of hexakis(n-methoxymethyl)melamine, 0.3 part of nitrocellulose having a nitrogen content of 10.5

25 hexamethylene dusocyanate at a mole ratio of 3 2 we1ght percent and havmg an average degree of polywere dissolved in a mixture solvent consisting of 3 parts merization of 150, a desired amount of tettamethyl siliof methanol, 50 parts of ethanol, 5 parts of n-butanol, cate set forth in Table 1 1 and 0.3 part of urethane modparts of methylethyl ketone and 2 parts of water.: ified polyethylene glycol prepared by reacting polyeth- Table 11 Mar resistance Amount of tetramethyl Film Gloss Transmission Run silicate of performance pencil retention a retention Abrasion No. (part) coated layer Adhesion hardness resistance 1 0 Good 100/100 411 43 63 100-120 2 0.003 Good 100/100 4H 4s 54 120-140 3 0.03 Good 100/100 411 46 66 200-220 4 0.3 Good 100/100 41-1 50 69 260-280 5 3.0 Good 100/100 41-1 47 67 280-300 6 6.0 Good 100/100 4H 43 67 260-280 7 7.0 irregular 100/100 3H 37 50 180-200 Reference Uncoated plate lrregular 2H 8 35 l-2 Separately, a 35 percent hydrochloric acid solution was diluted with methanol to obtain a 0.8 N solution. The

resulting solution was mixed with the above-described;

solution at a volume ratio of 1 1. After the resulting solution was left to stand at 25C. for 3 hours, an injection-molded lens of methylmethacrylate copolymer containing 1.5 mole percent methyl acrylate unit was in the solution for 20 seconds. Then, the lens was reylene glycol having an average molecular weight of 1,000 and hexamethylene diisocyanate at a mole ratio of 3 z 2 were dissolved in the same mixture solvent as in Example 10. Separately a 35 percent hydrochloric acid solution was diluted with methanol to obtain a 1.1 N solution. The resulting solution was mixed with the above-described solution at-a volume ratio of l 1. After the resulting solution was left to stand at 25C. for 5 hours, a 10 cm. X 10 cm. extruded plate of 3 mm. thick methylmethacrylate copolymer containing 6 mole percent of methylacrylate unit was immersed in the solution for 30 seconds. Then, the plate was re- Table 10 Half life Transtime of Ethen'fied Gloss mission charged methylol Pencil retention retention Abrasion static melamine Adhesion hardness resistance (sec.)

Methoxy 100/100 4H 260-280 50 50 compound Ethoxy /100 411 220-240 45 59 42 compound lsopropoxy 100/100 311 -180 33 52 31 compound Reference 2H 1-2 9 41 10,000

Uncoatcd plate moved from the solution and subjected to curing reaction at 80C. for 2 hours in a hot air drier. The thickness of a coating was 3 microns. The same tests as in Example 10 were carried out and the results are shown in Table l 1.

EXAMPLE I2 30 parts of hexakis(methoxy methyl)melamine, 0.3 part of the same nitrocellulose as in Example 3, 6 parts of urethane modified polyethylene glycol prepared by reacting polyethyleneglycol having a molecular weight lar weight of 400, 1.0 part of the oil soluble dye set forth in Table 13 and 0.3 part of nitrocellulose having a nitrogen content of l 1.9 weight percent and an average degree of polymerization of 85 were dissolved in a mixture solvent consisting of 49 parts of ethanol, 4 parts of n-butanol, 46 parts of methylethyl ketone and 1 part of water. Separately, a 35 percent hydrochloric acid solution was diluted with methanol to obtain a 1.0N solution. This solution was mixed with the abovedescribed solution at a volume ratio of l 1. After the resulting solution was left to stand at 25C. for 5 hours, a cm. X 10 cm. extruded plate of 3 mm. thick methylmethacrylate copolymer containing 6 mole percent of methylacrylate unit which was well washed was immersed for seconds. The thickness of a coating was 2 microns. Then, the plate was removed from the solution and subjected to curing reaction at 80C. for 1 hour in a hot air drier. The results of tests are shown in Table 13.

Table 13 Antistat Mar Half life resistance time of Gloss of Gloss charged Run Color index Degree of Pencil mirror retention static No. of dye coloring Adhesion hardness plane (sec.)

l Solvent red 84 4 100/I00 4H 89 S3 4 2 Solvent blue 45 4 100/I00 4H 89 55 4 3 Solvent violet 21 4 100/I00 4H 87 49 4 Reference 2H 75 8 8,000

Uncoated plate Note: C.l. Solvent red 84: "Spilon red GEH" made by Hodogaya Chem. lnc. Co., Ltd. C.l. Solvent blue 45: Savinyl blue RS made by Sandoz A.G. C.l. Solvent violct 2|: "Spilon violet RH" made by Hodogaya Chem. Inc. Co.. Ltd.

no] to obtain a 0.8 N solution. This solution was mixed P E 14 with the above-described solution at a volume ratio of l 1. After the resulting solution was left to stand at 20C. for 1 hour, a 6 cm. X 6 cm. cast plate of 3 mm. thick polymethylmethacrylate which was sufficiently washed and dried, was immersed in the solution for seconds. Then the plate was removed from the solution and placed in a hot air drier and subjected to curing reaction at 100C. for 1 hour. The thickness of a coating was 2 microns. The degree of coloring was judged by eyes. The degree of coloring 1. means that a coloring is hardly observed and that of 5 means that the deepest coloring is observed. The degrees of coloring 2, 3 and 4 lie between the degree of coloring l and 5.

30 parts of hexakis(methoxymethyDmelamine, 5 parts of urethane modified polyethyleneglycol prepared byreacting polyethylene-glycol having an average molecular weight of 1,000 and hexamethylene diisocyanate at a mole ratio of 2 l and 0.3 part of nitrophoric acid, 18 parts of oxalic acid or 18 parts of acetic Table 12 Mar . resistance Amount Gloss Run of dye Degree of Pencil Specular retention No. (part) coloring Adhesion hardness gloss (96) l 0 l l00/l00 SH 100 69 2 0.03 l l00/l00 SH 100 69 3 0.l5 2 l00/l00 5H 95 67 4 0.6 4 l00/l00 5H 93 5 1.8 5 100/I00 4H 90 65 6 2.] 5 70/100 3H 87 56 Reference 3H 11 Uncoated plate EXAMPLE l3 acid were dissolved in or mixed with 46 parts of metha- 30 parts of hexakis(methoxymethyl)melamine, 1.5 parts of polyethyleneglycol having an average molecunol, respectively. Each of these solutions or mixtures was mixed with the above-described solution and the tests are shown in Table 14.

group R is CH CH group; m represents an positive integer; and n is an integer of l to [0, and (D) about 0.01 to 12 moles, based on one mole of said etherified methylolmelamine, of an acid catalyst.

2. A composition as claimed in claim 1, containing about 0.1 to 20 parts by weight of tetramethyl silicate or tetraethyl silicate.

3. A composition as claimed in claim 1, containing about 0.5 to 6 parts by weight of an oil soluble dye.

4. A composition as claimed in claim 2, containing Table 14 Antistat Mar reslstance Gloss Transmission life time of Run Pencil retention retention charged static No. Acid catalyst Adhesion hardness (36) (31:0,)

1 p-toluenesulfonic acid 100/100 6H 73 87 I5 2 Phosphoric acid 100/100 4H 6| 74 8,5

3 Oxalic acid 100/100 5H 63 78 I0 4 Acetic acid l00/l00 4H 60 2.1 Reference 3H ll 65 Uncoated plate What is claimed is:

l. A composition for coating surfaces of shaped article of synthetic resins which comprises (A) I00 parts by weight of an etherified methylolmelamine of the formula wherein R represents an alkyl group having 1 to 4 carbon atoms, (B) about 0.01 to 5 parts by weight of a nitrocellulose, (C) about 1 to parts by weight of at least one alkyleneglycol selected from the group consisting of:

about 0.5 to 6 parts by weight of an oil soluble dye.

5. A composition as claimed in claim 1, wherein said acid catalyst is used in an amount of about 0.5 to 2. moles per mole of the etherified methylolmelamine.

. 6. A composition as claimed in claim 5, wherein said acid catalyst is selected from the group consisting of hydrochloric acid, phosphoric acid, oxalic acid, p-toluenesulfonic acid and acetic acid.

7. A composition as claimed in claim 1, wherein said nitrocellulose has a nitrogen content of about 9 to 12.5 weight percent and an average degree of polymerization of about 30 to 1,000.

8. A shaped article of a synthetic resin, the surfaces of which are coated with a layer which is the heat-cured product of the composition comprising (A) parts. by weight of an etherified methylolmelamine of the formula z ucmonm wherein R represents an alkyl group having 1 to 4 carbon atoms, (Blabgul 0.01 to 5 parts by weight of a nitrocellulose, (C) about 1 to50 parts by weight of at least one alkyleneglycol selected from the group consisting of:

resents Zll group wherein R represents an alkylene group having 1 to 14 carbon atoms, phenylene or cyclohexylene group; R represents an alkylene group having 2 to 17 carbon atoms, phenylene or cyclohexylene group; R represents an alkyl group having 1 to 8 carbon atoms and when X represents group R is -CH CH group; m represents an positive integer; and n is an integer of l to 10, and (D) about 0.01 to 12 moles, based on one mole of said etherified methlolmelamine, of an acid catalyst.

9. A shaped article according to claim 3, wherein the synthetic resin is selected from the group consisting of polymethylmethacrylate methylmethacrylate copolymer containing about 0.5 to 15 mole percent of methylacrylate unit, polyamide, polycarbonate, cellulose diacetate, cellulose triacetate, acrylonitrile-butadienestyrene copolymer and unsaturated polyester.

Ell. A shaped article according to claim 8, wherein said composition contains about 0.1 to parts by weight of tetramethyl silicate or tetraethyl silicate.

ill. A shaped article according to claim 10, wherein said composition also contains about 0.5 to 6 parts by weight of an oil soluble dye.

12. A shaped article according to claim 8, wherein the thickness of said layer is about 0.5 to 30 microns.

13. A shaped article according to claim 10, wherein said shaped article is a lens of methylmethacrylate copolymer containing about 0.5 to 15 mole percent of methylacrylate unit.

M. A shaped article according to claim 10, wherein said shaped article is a plate of polymethylmethacrylate.

115. A process for improving surface properties of a shaped article of a synthetic resin which comprises coating a shaped article of a synthetic resin with a solution of a composition comprising (A) 100 parts by weight of an etherified methylolmelamine of the formula I UCI-hO R )z wherein R represents an alkyl group having its 1 carbon atoms, (B) about 0.01 to 5 parts by weight of a nitrocellulose, (C) about 1 to 50 parts by weight of at least one alkyleneglycol selected from the group consisting of:

H- OR OR Ol-l and H 0R ),,,-X- R 0 )-l-l wherein R represents Cll,CH CH CH(CH or -(Cll-l group; p is O or a positive integer; X represents group wherein R represents an alkyle i'ie group having 1 to 14 carbon atoms, phenylene or cyclohexylene group; R represents an alkylene group having 2 to 17 carbon atoms, phenylene or cyclohexylene group; R represents an alkyl group having 1 to 8 carbon atoms and when X represents group R is CH CH group; m represents an positive integer; and n is an integer of l to 10, and (D) about 0.01 to 12 moles, based on one mole of said etherified methylolmelamine, of an acid catalyst, and heatcuring the resulting coating at a temperature of from about 50C. to the temperature below the heat distortion temperature of said synthetic resin.

16. A process as claimed in claim 15, wherein said composition contains about 0.1 to 20 parts by weight of tetramethyl silicate or tetraethyl silicate.

117. A process as claimed in claim 15, wherein said composition also contains about 0.5 to 6 parts by weight of an oil soluble dye.

18. A process as claimed in claim 15, wherein said synthetic resin is a polymer selected from the group consisting of polymethylmethacrylate, polyamide, polycarbonate, cellulose diacetate, cellulose triacetate, acrylonitrile-butadiene-styrene copolymer and unsaturated polyester and the solvent for said composition is a mixture solvent essentially comprising of (a) at least one alcohol, (b) chloroform, (c) at least one acetate and ((1) water.

19. A process as claimed in claim 15, wherein said synthetic resin is a methylmethacrylate copolymer containing about 0.5 to 15 mole percent of methylacrylate unit and the solvent for said composition is a mixture solvent essentially comprising (a) at least one alcohol, (b) at least one ketone and (c) water.

20. A process as claimed in claim 15, wherein said acid catalyst is selected from the group consisting of hydrochloric acid, phosphoric acid, p-toluenesulfonic acid, oxalic acid and acetic acid.

' 2 53? v UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 Dated January 15, l974' Inventor) Noboru Tanimura et a1 It is certified that error appears in the above-identified pate no and that said Letters Patent are hereby corrected as shown below:

Col. 9, Table 4, utxder Heading "Adhesion't, Run No. 2, change "62/10" to 62/100 A A I Col. 22, lines l 2 and 3, Claim 15, can eel in their entirety arid substitute therefor V v H--(OR -OR 0H and Signed and sealed this 27th day of August 1974.

( EA 1. Attest:

MCCOY M. GIBSON, JR. C. MARSHALL DANN Art-testing Officer v Commissioner of Patents 

2. A composition as claimed in claim 1, containing about 0.1 to 20 parts by weight of tetramethyl silicate or tetraethyl silicate.
 3. A composition as claimed in claim 1, containing about 0.5 to 6 parts by weight of an oil soluble dye.
 4. A composition as claimed in claim 2, containing about 0.5 to 6 parts by weight of an oil soluble dye.
 5. A composition as claimed in claim 1, wherein said acid catalyst is used in an amount of about 0.5 to 2 moles per mole of the etherified methylolmelamine.
 6. A composition as claimed in claim 5, wherein said acid catalyst is selected from the group consisting of hydrochloric acid, phosphoric acid, oxalic acid, p-toluenesulfonic acid and acetic acid.
 7. A composition as claimed in claim 1, wherein said nitrocellulose has a nitrogen content of about 9 to 12.5 weight percent and an average degree of polymerization of about 30 to 1,
 000. 8. A shaped article of a synthetic resin, the surfaces of which are coated with a layer which is the heat-cured product of the composition comprising (A) 100 parts by weight of an etherified methylolmelamine of the formula
 9. A shaped article according to claim 8, wherein the synthetic resin is selected from the group consisting of polymethylmethacrylate methylmethacrylate copolymer containing about 0.5 to 15 mole percent of methylacrylate unit, polyamide, polycarbonate, cellulose diacetate, cellulose triacetate, acrylonitrile-butadiene-styrene copolymer and unsaturated polyester.
 10. A shaped article according to claim 8, wherein said composition contains about 0.1 to 20 parts by weight of tetramethyl silicate or tetraethyl silicate.
 11. A shaped article according to claim 10, wherein said composition also contains about 0.5 to 6 parts by weight of an oil soluble dye.
 12. A shaped article according to claim 8, wherein the thickness of said layer is about 0.5 to 30 microns.
 13. A shaped article according to claim 10, wherein said shaped article is a lens of methylmethacrylate copolymer containing about 0.5 to 15 mole percent of methylacrylate unit.
 14. A shaped article according to claim 10, wherein said shaped article is a plate of polymethylmethacrylate.
 15. A process for improving surface properties of a shaped article of a synthetic resin which comprises coating a shaped article of a synthetic resin with a solution of a composition comprising (A) 100 parts by weight of an etherified methylolmelamine of the formula
 16. A process as claimed in claim 15, wherein said composition contains about 0.1 to 20 parts by weight of tetramethyl silicate or tetraethyl silicate.
 17. A process as claimed in claim 15, wherein said composition also contains about 0.5 to 6 parts by weight of an oil soluble dye.
 18. A process as claimed in claim 15, wherein said synthetic resin is a polymer selected from the group consisting of polymethylmethacrylate, polyamide, polycarbonate, cellulose diacetate, cellulose triacetate, acrylonitrile-butadiene-styrene copolymer and unsaturated polyester and the solvent for said composition is a mixture solvent essentially comprising of (a) at least one alcohol, (b) chlorOform, (c) at least one acetate and (d) water.
 19. A process as claimed in claim 15, wherein said synthetic resin is a methylmethacrylate copolymer containing about 0.5 to 15 mole percent of methylacrylate unit and the solvent for said composition is a mixture solvent essentially comprising (a) at least one alcohol, (b) at least one ketone and (c) water.
 20. A process as claimed in claim 15, wherein said acid catalyst is selected from the group consisting of hydrochloric acid, phosphoric acid, p-toluenesulfonic acid, oxalic acid and acetic acid. 